Hide checkout link if quantity is greater than 1 of three specific products in cart

Question

We'd like to hide the Proceed to Checkout button on the Cart page if any quantity greater than 1 total of a set of 3 products are in the cart.

In other words, the customer can only buy a max of ONE of the following Product IDs: 4, 44, and 47. I'd like to simply check the cart and total a count of all 3 of those Ids in their cart. If it's any more than 1 total, then I want to hide the Proceed to Checkout button (and likely echo a note like "You can only buy 1 total of the special products")

I'm using the link.phtml template and figured I need to cycle thru the Cart quote to tally the count in cart of those three products. And of course, if more than 1 then display the message, else display the checkout button.

I've looked at and tried other examples of checking for products in cart, but can't wrap my head around checking for an array of 3 products and tallying the total count. Any help would be appreciated.

Answer 1

From an answer of mine over on StackOverflow in 2013:

Using an event observer you could listen to the postdispatch of the cart view event and suppress the button from displaying. This is a builtin functionality.

<events>
    <controller_action_postdispatch_checkout_cart_index>
        <observers>
            <yourmodule_postdispatch_delete>
                <class>yourmodel/observer</class>
                <method>deletePostdispatch</method>
            </yourmodule_postdispatch_delete>
        </observers>
    </controller_action_postdispatch_checkout_cart_index>
</events>

And the observer method would look like:

public function deletePostdispatch($observer)
{
   if(Mage::getSingleton('checkout/session')->getQuote()->getItemsCount()==1){

       Mage::app()->getStore()->setConfig('checkout/options/onepage_checkout_enabled',0);
   }

}

---

_Source:

https://stackoverflow.com/a/18347019/582138

Answer 2

I essentially figured out what I needed by using the getQuote and getAllItems to iterate thru. The below code is quick and dirty and needs cleanup, but I just needed to know if customer has more than 1 of any of the 3 productIds in total in cart.

// Product IDs of Free Products
    $arrayProds = array(4,44,47);
    $count = 0;

$cart = Mage::getModel('checkout/cart')->getQuote();
foreach ($cart->getAllItems() as $item) {
    $productId = $item->getProductId();
    if (in_array($productId,$arrayProds)){
            $productQty = $item->getQty();
            $count = $count + $productQty;
            if ($count > 1){
                // We know that we have too many free products in cart, and can do whatever we want here
                break;          
            }
    }
}

For now this works, but understandably there's probably a better way of doing this?